It is known that certain compositions of soap bars have properties which are perceived by users and which may be modified by subjecting the soap, as a solid or semi-solid mass, to mechanical working. A well known example includes the processing of transparent soaps (U.S. Pat. No. 2,970,116).
We have discovered that such modifications arise from changes in the composition and structure of the phases present in the soap mass. Moreover, we have found that with conventional methods such changes only occur within a limited region of the volume subjected to mechanical working.
The phases referred to herein are those detectable by X-ray investigation but include changes in the domain size of the phases present, even when no change in the proportion of phases occurs.
The present invention utilises processing conditions to achieve phase change by subjecting the soap-containing feedstock to considerable working within a specific temperature range in an efficient manner; the temperature range being sensitive to the composition.
The soap-containing compositions of the invention are sensitive to the application of shear in that they undergo phase changes when subjected to shear.
The phase structure of soaps is discussed in `Industrial Oil and Fat Products` of Bailey (Ed D Swern) Volume I, 4th Edition. The phase associated with soap leaving the drier is omega. The Applicants view the beta phase as associated with physical hardening of bars and transparency and delta phase with the improvement of lather and mush properties of a superfatted material.